Apparatus for controlling the tension in a running web



May 9, 1961 c. AARON ETAL 2,983,463

APPARATUS FOR coNTRoLLING THE: TENSION IN A RUNNING WEB Filed March 21,1957 IN VEN TORS CHARLES AA EON BY LEON/IPD CKSTKOM United States Patenti APPARATUS FOR CONTROLLING THE TENSION IN A RUNNING WEB Charles Aaron,West Caldwell, and Leonard Rockstrom,

Madison, NJ., assignors to Cameron Machine Company, Brooklyn, N.Y., acorporation of- New York Filed Mar. 21, 1957, Ser. No. 647,558

4 Claims. (Cl. 2421-7543) This invention relates to a mechanism useful,`with or as a part of a web-winding machine, for maintaining asubstantially constant tension in a web which is being run from apay-out roll to a take-up roll in such a machine to permit processing ofthe web as itmoves between the two rolls. One of several reasons whysuch tension-maintenance kis important is the avoidance of web breakageor damage which might occur under excess or non-uniform tensionconditions.

An important object of this invention is the provision o f meanscontrolling a condition affecting the web ten# sion, which means areresponsive to changes in web tension to cause such controlling meansautomatically to compensate for such changes.

A condition commonly affecting web tension is the braking effect appliedand maintained upon the pay-out roll; and the mentioned object and othermore or less specific objects are achieved in a preferred form of thisinvention by utilizing the torque present at the shaft of a motor whichdrives the take-up roll to control a brake on the pay-out roll. In suchan arrangement an increase in torque at a motor which drives the take-uproll indicates a need for reduced braking effect at the pay-out roll inorder to avoid such high tension in the web as to break or damage thelatter.

Although the concepts of this invention may be utilized in mechanisms ofvarious designs, nevertheless, it is illustrated in the accompanyingdrawing as utilized in only one of various possible embodiments without,however, limiting the invention to that particular embodiment.

The drawing is a diagrammatic view of a preferred embodiment of thisinvention, some portions or components being shown in perspective asviewed from the underside thereof, other portions or components beingshown more or less in the form of symbols, and the arrangement ofcomponents in the drawing being such as to facilitate an understandingof the invention without regard to the particular location of some ofthe components in practice and without regard to the particulararrangement of piping that would be employed in an actual installation.

The illustrated apparatus comprises a pay-out roll 10, a take-up roll12, a pair of driving rollers 14 and 16, guide rollers 18 and 20, and acutting mandrel 22 between which and a circular cutting knife 24 a web Wpasses in running from pay-out roll 10, and past guide rollers 18 and 20to take-up roll 12 in the process of being slitted into two separatewebs each of about half the width of the web as in its original form onroll 10.

The web may be of paper, cellophane or other plastic, or of metal foilor, indeed, any type of web material used in industry. The showing ofthe cutting mandrel 22 and the cutting knife 24 is only to indicate thatthe purpose of passing the web from roll to roll 12 is merely to processit in some manner. The processing need not necessarily be slitting, butit may be in the form of printing or glazing the surface of the web orotherwise processing the web.

tension-adjusting valve 72,

2 All the mentioned rolls and rollers are mounted so that they may turnon parallel axes. In a strict sense, the part of the machineconstituting the take-up roll 12 may be merely'a shaft or thin drum 26,and the pay-out roll 10 may be merely a shaft 28 with which isassociated a suitable brake device 30. In this sense, the indicatedrolls 10 and 12, therefore, are merely rolls of web material. Exceptwhere essential to an understanding of the invention, shafts andsupporting framework have been omitted, as the type, disposition, andconventional manner of support of such parts are well known to thosefamiliar with this art. f

The web W is caused to move from pay-out roll 10 onto roll 12 to becomea part of the latter,'by the driving rollers 14 and 16, which are turnedby a suitable motor 32 through a gear 34, suitably keyed to a shaft 68of the armature of said motor, and gears 36 and 38 which mesh with andare'driven'by: gear 34; the gears 36 and 38, respectively, being keyedupon shafts 40 and 42 of rollers 14 and 16. The shaft26 is a floatingshaft and the roll 12 of accumulated web material issupported upon andturned frictionally by the two rollers 14 and 16.

The brake deviceY 30,1as illustrated, consists of brakearms 44, 46,pivoted attheir lower ends at fixed points andlinked together towardtheir upper ends by a fluidpressure-operated assembly consistingof'acylinder 48 pivoted to brake-arm 46 and a piston 50, within the cylinder48, having a rod 52 extending through one end of said cylinder andpivoted to brake-arm 44.

The brake-arms 44 and 46 are fitted with suitable brakeshoes 54, whichengage'shaft 26.to exert a braking force upon the latter. The upper ends.of the brake-arms 44 and 46 are normally urged apart, tending to4relieve pressure or contact of the brake-shoes with respect to theshaft 28, by means of a compression coil spring 56, which extends abouta rod 58 one end of which is pivoted to arm 44 and the other end ofwhich extends slidably through the upper end of arm 46. The spring 56 iscompressed between the arm 46 and a collar 60 fixed upon rod 58 at apoint near arm 44.

The motor 32 is supported in opposite walls 62, 64 of a bracket 66which, in practice, would be mounted rigidly either upon some part ofthe frame of the machine or upon some fixed element or member adjacentto the machine. The motor isf-supported at its opposite ends., coaxiallyof the shaft 68, by the walls 62, 64, andthe motorv mounting is suchthat, except as restrained as hereinafter explained, the body or casinglof the motor 32 is capable of torsionally induced angular or rotarymove-` ment relative rto the bracket 66. According to the presentinvention, a controllable restraint is imposed against such rotation ofthe motor and, to the extent that sucli restraint permits limitedrotation of the motor about its axis, such limited rotation is utilizedin controlling the tension in the running web.

In the illustrated embodiment, control of the webs tension isaccomplished through instrumentalities which control and/or arecontrolled by fluid under pressure, and such pressurized fluid isutilized, also, to operate the brake device 30. These instrumentalitiescomprise a tension-sensing cylinder or dash-pot 70, a tension-adjustingvalve 72, a tension-control valve 74, and a gauge 76, al1 arrangedsubstantially as shown in the drawing. f

The tension-sensing cylinder 70 preferably has therein a piston ordiaphragm 78 defining, with the casing of the cylinder 70, a pressurechamber 80 wherein is maintained fluid under pressure communicated intoit from a main supply pipe 82 through a branch pipe 84, the mentionedand a connecting pipe 86, the pipe 82 of course being connected to theindicated supply of fluid, preferably air, under pressure. Ilfhus, thepres,

; M I l sure chamber 80 constitutes biasing means and is someripherallyand fluid-tightly secured, marginal portion .S8

of sueient strength to withstand `pressures developed in chamberr 30.Rigidly 4fixed to the piston 78'is a vpiston rod 90 which extendsoutwardly through the casing of the Ycylinder 70 and is pivoted at itsouter end to an arm 92 which is rigidly mounted on or is a rigid,integral part of the body or casing of motor 32. Chamber 94 of thecylinder 70, through which the piston rod 90 extends, is suitably ventedto ambient atmosphere through a port 96. The end of cylinder 70 oppositeto the piston rod 90 has a rigid bracket 98, pivoted to a bracket 100which is'rigidly mounted either upon an` adjacent portion of the frameof the lmachine or upon some other, adjacent, fixed surface. Thedescribed pivot lmounting ofthe cylinder 70 is such that said cylindermay oscillate slightly in response to oscillations of the arm oractuating member 92, the pipe 86 of course being at least slightlyflexible or flexibly connected to the cylinder 70 to permit thementioned oscillation of the latter.

The tension-adjusting valve 72 may be a more or less conventionalpressure-regulating'valve such as is used on fluid-pressure lines tocontrol the pressure of luid in or moving through such lines. Theillustration of the valve 72 in the drawing, while diagrammatic, shouldsu'ice to convey an understanding of the nature of the operation of thevalve and the nature of its efect upon other parts of the disclosedapparatus.

Referring to the drawing, the valve 72 is formed with a linepressurechamber 72LP, a regulated-pressure chamber 72RP, and a vent chamber 72Vsuitably vented to ambient atmosphere lby a port 102. A valve port 104with a'valve element 106 therein controls the passage of uid betweenchambers 72LP and 72RP. The valve element 106 is normally held in aclosed position in port 104 by means of a compression coil spring 108.

The valve 72 also has manually operable operating means in the form ofan adjusting screw 110'having on its outer end a knob or handle 112 bymeans of which it may be manually turned. The screw 110 is threadedthrough the top of the casing of the valve 72, and, compressed betweenits lower end and a centrally apertured, central valving disk 118 of aflexible diaphragm 120, is a compression coil spring 114. The upper endof the valve element 106 is formed as a needle-valve which seats inaperture 116 of valving disk 118, the latter and the upper end of valveelement 106 functioning as a valve permitting controlled passage ofpressurized fluid from chamber 72RP to chamber 72V in the operation ofthe device.

By manipulation of the knob 112,'the screw 110 may be turned down toincrease the compression on spring 114 and thereby move Valve element106 downwardly to open port 104. This permits fluid under pressure topass from chamber 72LP into chamber 72RP, and thence through pipe 86into pressure chamber 80 of the tensionsensing cylinder 70. When thepressure in chambers 80 and 72RP builds up to a pressure correspondingto the setting of screw 110, the pressure in chamber 72RP, actling uponthe underside of diaphragm 120, opposes the force of spring 114, therebyenabling spring 108 to shift the valve element 106 to its closedposition in port V104. If, through leakage or otherwise, there should beany loss of pressure in chamber 80,'the reduced pressure on theunderside of diaphragm 120 enables spring 114 to open valve element 106relatively to port 104 suiciently to bring about restoration of thedesired pressure in said chamber. If it is ydesired to decrease thepressure in chamber 80 by manual control, the screw 110 is turned up oreased off, thereby reducing the compressive force of .spring .114, whichpermits valving disk 118 to rise 'to Vcause the upper end of valveelement 106 to become un- @essaies j j f,

seated from within the aperture 116, thereby permitting uid from chamber72RP to pass into chamber 72V and thence through port 102 to ambientatmosphere. The gauge 76 is connected, in the manner indicated, to pipe86. The graduations on the gauge may be direct pressure indicationsand/0r direct tension indications.

. The tension-control valve 74 may be substantially vthe same as valve72 except in having the regulating plunger 122 as a movable controlmember in place of the screw 110. The plunger 122 is arranged to sliderather than to turn relatively to the valve casing,.and the vouterend'of the plunger 122 is preferably rounded or provided with anintegral, ball-shaped end for coaction with a cam 124 which at one endis pivotally mounted upon arm 92 and at its other end is equipped withan adjusting link 126 extending through an aperture in a lug 128rotatably mounted in the arm y)2. ri`he adjusting link is threaded atthe point where it passes through the lug 128 and is provided thereatwith adjusting lock-nuts 130 by adjustment of which it is possible toadjust the angularity ofthe cam 124 in relation to the `upper end oftheplunger 122. The `indicated 'supply of compressed air is connected bypipe 82 to line pressure chamber 74LP `of "the tension-control valve,and chamber 74RP of said valve is connected by a pipe 132 to the brakecylinder 48 in the manner indicated in the drawing.

In operation of the Windingmachine :as diagrammatically illustrated, itmay be assumed that ythe motor 3.2 operates only unidirectionally todrive the various gears, rolls, rollers and shafts in the directionsindicated directional arrows in the drawing. At the beginning of a passof the web W to andpast the circular cutting knife 24 or otherequivalent web-processing apparatus, the pay-out roll 10 containingsubstantially the entire length of the web will be at its greatestydiameter While ,only several or at least very few turns of the web willbe on the shaft or drum 26l so that the diameter of the take-up roll 12will be at a minimum. As the ,pass of the-web progresses, roll 10progressively decreases in diameter and, consequently, the mechanicaladvantage in favor of the force pulling the web from the roll 10decreases in relation to the braking force applied at shaft 28, so thatif said braking force is permitted to remain constant, the tension inthe web will `progressively increase and thereby the web will becomedamaged or broken. Such increased tension is reflected in'increasedtorque at the motor 32 and the disclosed control system of thisinvention immediately utilizes even a slight increase in such torque toease theY braking effect and thereby maintain substantially uniformtension in the web during its pass from roll 10 to roll 12,.

Let it be assumed that valve 72 has been set at the beginning of a pass.to what may be termed a normal setting which will maintain such,pressure `constantly in chamberof valve 70 kas will enable diaphragm.78 toFsupport the body of motor 3.?, against rotation -at that degreeof torque which corresponds to the desired degree of web tension. As thepass progresses and the diameter of roll 10 decreases, `the torque atthe motor `tends to increase but such tendency Vimmediately causes arm92 to rotate clockwisely slightly and slightlydepress dial phragm 78thereby momentarily increasing the pressure in chambers .80 -and 72RP.Such increased pressure `in chamber 72RP causes valving ,disk v118 torise, thereby opening aperture 116 Vto vent ofi the excess pressure',leaving the arm 92 in its slightly changed, newly acquired position.

The mentioned movement of `the arm 92 to its new .position causes cam124 to move similarly. and permit `plunger 122 to Vmove outwardlyslightly in Vvalve 74, `thereby reducing the pressure in chamber MRP andvin the brake-cylinder 48 to the .extent necessary to give compensationin the braking effect for the reductionthus farencountered in themechanical advantagejat -the roll s by reason of the reduction in thelatters diameter. Such compensation in the braking effect and thedescribed maintenance of uniform torque at the motor 32 assure tsubstantially uniform web tension throughout the pass.

It will be understood that during a camplete pass of the web, the arm 92repeatedly undergoes the slight back to its original position inpreparation for another Y web-winding operation. Suitable abutments orstops (not shown) may be provided to limit movement of arm 92 inopposite directions and thereby protect the diaphragms in cylinder 70and valve 74 against being accidentally ruptured.

It should be understood that the concepts of the disclosed improvementsmay be utilized in various other Ways without, however, departing fromthe invention as set forth in the following claims.

We claim:

1. Apparatus for controlling tension in a running web moving from apay-out roll to a take-up roll, comprising a motor connected to thetake-up roll for driving the latter and rotatably mounted to permitlimited bodily rotation of said motor in response to torque variationsthereat resulting from variations in the tension of the web, a brake,independent of said motor and coacting with said pay-out roll to opposeturning of the latter, and tension-control means for controlling theoperation of said brake, said tension-control means being connected tosaid motor whereby to operate in response to said bodily rotation of themotor and connected to said brake to so control the latter as tocompensate for such tension variations; said brake being iiuid-operatedand said tension-control means including a tension-control valve incontrolling relation to said brake and coacting with said motor duringthe latters bodily rotation to derive adjustment of said valve,proportionate to such bodily rotation; said tension-control meansfurther including a huid-pressure, tension-sensing cylinder coactingwith said motor in opposition to such bodily rotation of the latter anda manually adjustable pressure-regulating valve adapted to control uidpressure in said cylinder and thereby control opposition to such bodilyrotation of the motor by said tension-sensing cylinder.

2. Apparatus for controlling tension in a running web moving from apay-out roll to a take-up roll, comprising a motor having a rotarydriving element adapted to turn the take-up roll -and a bodily rotatablecasing with an integral, rigid, radial arm adapted to undergo limitedangular movement with said casing in response to variations in thetorque present between said rotary element and said casing, afluid-operated brake adapted to control the freeness of rotation of thepay-out roll, a tensionsensing lhuid-pressure cylinder coacting withsaid arm to afford huid-pressure opposition to angular movement of themotor casing, manually operable means for controlling the pressure offluid in said cylinder acting in opposition to such angular movement,and a pressureregulating valve, coacting with said arm, as the lattermoves angularly, to control the supply of fluid to said brake to so varythe latters operation as to compensate for variations of the tension ofthe web.

3. Apparatus for controlling tension in'a running web moving from apay-out roll to a take-up roll, comprising a motor connected to thetake-up roll for driving the latter and rotatably mounted to permitlimited bodily rotation of said motor in response to torque varationsthereat resulting from variations in the tension of the web, a brake,independent of said motor and coacting with said pay-out roll to opposeturning of the lat 7 ter, and tension-control means'for controlling theoperation of said brake, said tension-control means being con nected tosaid motor whereby to operate in response to said bodily rotation of themotor and connected to said brake to so control the latter as tocompensate for such tension variations; said brake being duid-operated,said motor Vhaving a rigid, radial arm, and said tensioncontrol meanscomprising a fluid-pressure, tension-sensing cylinder having a diaphragmtherein and a rod connected between the diaphragm and said arm, anadjustable pressure-regulating valve controlling the supply of iluid tosaid cylinder in back of said diaphragm -to oppose rotation of said arm,a pressure-regulating valve controlling the supply of fluid 4to saidbrake, and al cam on said arm adapted to coact with and control theoperation of the latter valve to cause such operation of the brake aswillsubstantially compensate for variations in the tension of the web.

4. Apparatus for controlling tension in a running web moving from apay-out roll to a take-up roll, comprising a lmotor having a rotaryshaft connected to the take-up roll for driving the latter and a casingmounted for limited rotation in response to torque variations at themotor resulting from variations in the tension of the web, a variablebrake, independent of said motor and coacting with the running web tooppose movement of the latter toward the take-up roll, brakeoperatingmeans for variably operating the brake, a movable control membercoacting with said brake-operating means to control the lattersoperation and thereby control operation of the brake, biasing meansyieldably opposing said limited rotation of the motor casing, and anactuating member,

, integral with said casing and arranged to engage and operably movesaid'control member, upon such rotation of the casing, to control thebrake-operating means and the operation of the brake.

References Cited in the le of this patent UNITED STATES PATENTS

